Scripture talks about the effectual fervent prayer of the righteous (James 5: 16), giving us an idea of two key attributes prayer must have to produce its desired result: it must be effectual; it must be fervent. To be effectual is to produce the intended result; entirely adequate. It is to be earnest, passionate, heartfelt, and continuous. It doesn't give up midway until it's desires are achieved.
To be fervent in prayer, requires exhibiting particular enthusiasm, zeal, conviction, persistence, or belief. It is to be glowing, and burning very hot, irrespective of your real-time situation. Fervency borders on your faith, your belief in God's ability to answer your heart's desires. It is healthy faith condition that makes tremendous power available in the place of prayer that births dynamic works. Prayer devoid of faith has nothing to stand on or expect.
When you're sincere and discerning, you'd know when your prayer is generating or not generating tremendous power. Prayer that doesn't move you, is unlikely to move God or swing the pendulum. This defeats also the erroneous thought that longevity is key that guarantees results in prayer. No, it is not in duration but in devotion. Deploy your faith passionately and be connected when you pray to get maximum results.